RingLists

A RingList is a list of distinct values that is unchanged by rotation. These can be created by giving a list of values or a one-dimensional array of values:

julia> using RingLists

julia> a = RingList(1,2,3,4);

julia> b = RingList([2,3,4,1]);

julia> a==b
true

julia> println(a)
[ 1 → 2 → 3 → 4 → 1 ]

Note the repeat of element 1 in the output showing that the list wraps around.

Functions

In this list, a stands for a RingList.

• length(a) gives the number of elements held in the RingList.
• keys(a) returns an iterator of the elements in a.
• haskey(a,x) checks if x is an element of the RingList.
• Vector(a) returns a one-dimensional array of the elements in a.
• Set(a) returns the elements of a (as an unordered collection).
• collect(a) returns the elements of a in an ordered list.
• copy(a) makes an independent copy of a.
• shuffle(a) returns a new RingList with the same elements as a but in randomized order.
• next(a,x) returns the next element after x in a; also a[x].
• previous(a,x) returns the element y with a[y]==x; also a(y).
• first(a) returns an element of a that is, if possible, the smallest element of a. Call first(a,false) to ignore trying to start at the smallest element. Fails if a is empty.
• delete!(a,x) removes x from the collection linking together its predecessor and successor.
• insert!(a,x) inserts the element a into the RingList. No guarantee where it will end up.
• insertbefore!(a,x,y) inserts x into a before y.
• insertafter!(a,x,y) inserts x into a after y. For example: ``` julia> a = RingList(1,2,3) [ 1 → 2 → 3 → 1 ]

julia> insertafter!(a,99,2)

julia> a [ 1 → 2 → 99 → 3 → 1 ]

* `reverse(a)` returns a new `RingList` with the elements reversed.

julia> a = RingList(1,2,3,4,5) [ 1 → 2 → 3 → 4 → 5 → 1 ]

julia> b = reverse(a) [ 1 → 5 → 4 → 3 → 2 → 1 ]

## Iteration

`RingList` elements can be iterated:

julia> a = RingList(1,2,3,4,5) [ 1 → 2 → 3 → 4 → 5 → 1 ]

julia> for x in a println(x) end 1 2 3 4 5